Fused disconnect or unfused, motor is fed from breaker...

I need to replace a disconnect to a piece of gear and I'm not sure.

At work we have a 480V, 3Phase, motor control center that feeds out to an evaporative cooler. This particular unit has two fans and a circulator pump.
One of the outdoor fan disconnects is in really bad shape and needs to be replaced (each fan has it's own disconnect). The current disconnect has fuses in it, but I'm not convinced they should even be there.

The motor controller is fed from a circuit breaker (not positive on the amps, I think it's an 80 or 100) which feeds the line side of the starter. The starter has heaters monitoring each leg. The local disconnect has 3 time-delay, 60 amp fuses in it.
Wouldn't the circuit breaker cover the wires and motor?
So fused, or unfused on the new disconnect?
Thanks

Fused disconnect or unfused, motor is fed from breaker...

Ya know one thing ., 480 volts that something IMO you should have electrician come out and have them fix this in safe manner and that is pretty good size disconnect switch @ 480 volts plus what more with triphase supply they need to be in correct sequince to run properly.

As far for multi motours they will requied a fused disconnect due the starter size is pretty big and it may not able detected the overloaded motour at all so that why they installed fused disconnect switch plus there is a code requirement due you are not in sight of breaker or master fuse load centré.

Sorry to be harsh but this part is not a really a DIY item when you mention 480 volts that is a commercal voltage level. Again just get a electrician to come out and they will do it in proper way.

Sorry if I didn't explain that well enough, I'll try again.
The 480V Motor Control Center feeds 21 different machines, pumps, etc.
Each load has it's own circuit breaker, motor starter w/heaters, stepdown transformer and (120V) control wiring.
The individual "cells" of the MCC are powered from fingers that stab around buss bars behind them, this energizes wires (jumpers about 6" long) that feed the circuit breaker.
Then there are wires that feed from the load side of the CB to the contactor right next to it. I'll have to post a photo.

We have two evaporative coolers located outdoors.
Each one has 3, 3 phase feeds from the MCC.
Two fan feeds, 1 circulator pump feed.
Each cooler has 3 disconnects, one for each load.
There is no tapping involved.
I'll stick with the fused disconnects.
(I thought I'd ask to see what you guys thought)

Fused disconnect or unfused, motor is fed from breaker...

Quote:

=Do It Right;611771]

Sorry if I didn't explain that well enough, I'll try again.
The 480V Motor Control Center feeds 21 different machines, pumps, etc.
Each load has it's own circuit breaker, motor starter w/heaters, stepdown transformer and (120V) control wiring.
The individual "cells" of the MCC are powered from fingers that stab around buss bars behind them, this energizes wires (jumpers about 6" long) that feed the circuit breaker.

I know what an MCC looks like and I know the other electricians do as well. I was just trying to figure out the 80-100 amp breaker at the MCC and the 60 amp fuses at the disco. I didn't read it well enough to realize this was all just one circuit.

2 things come to mind: there is a max circuit limitation for the equipment and the 60 amp fuses would be necessary to meet that requirement OR this was set up so when working on the thing, you take some 60 amp fuses with you so if you pop the circuit, you don't have to walk all the way back to the MCC to reset the circuit because the 60 amp fuses should pop before the 80-100 amp breaker would trip.

Since a 60 amp fused disco is going to be cheaper than changing to a non-fused disco and changing the breaker (if necessary), just toss the fused disco on there and be done with it.

.

Quote:

....and 2 Caterpillar Diesel generators, 800A each

Oh, just couple small generators then? all that POCO power available and only these 2, relatively small, generators?